Washington Territory was created 14 February 1859 when State of Oregon was admitted to the union on the same day.
The territory contained entire what is now state of Washington, northern part of Idaho and northwest portion of Montana (west of the continental divide.)
The territorial capital was Olympia. It is now state capital of the State of Washington.
Idaho Territory was created 4 March 1863 and contained all that is now State of Idaho, annexing the Washington Territory's portion of Idaho and Montana.